The present invention relates to a locking device for use in a cargo support to lock a retractable tube, and more particularly to such a locking device, which fits different retractable tubes.
In a motor truck, a cargo support may be used to support cargo in place, preventing cargo from falling down. The cargo support has a retractable tube for adjustment, and a locking device controlled to lock the retractable tube. FIGS. 7 and 8 show a locking device 6 comprises a holder frame 61 made of aluminum, a locking block 62 made of copper, a rack 63, and a driving lever 64. This structure of locking device is still not satisfactory in function. The drawbacks of this structure of locking device are outlined hereinafter.
1. The holder frame 61 must be use with a retractable tube having an outer tube of circular cross section.
2. Because the holder frame 61 and the locking block 62 are respectively made of aluminum and copper, the manufacturing cost of the locking device 6 is high, and the connection area between the holder frame 61 and the locking block 62 tends to be damaged.
3. The bearing face 610 of the holder frame 61 which support the rack 63 wears quickly with use. When the bearing face 610 starts to wear, the rack 63 tends to be forced out of the engaged position, causing the driving lever 64 unable to drive the rack 63 positively.
The present invention provides a locking device, which eliminates the aforesaid drawbacks. According to the present invention, the locking device comprises a holder frame fastened to the outer tube of the retractable tube, a rack moved in a longitudinal sliding way defined between two parallel lugs of the holder frame, a driving lever pivoted to the holder frame for moving the rack, a locking block pivoted to the holder frame and retained by a spring to lock the driving lever, and a L-shaped locking plate mounted in the holder frame for the positioning of the outer tube of the retractable tube. The locating plate comprises a round hole on a transverse section thereof through which the inner tube is inserted into the outer tube, two stop flanges bilaterally extended from a longitudinal section thereof and respectively engaged with respective end notches on the holder frame, and a lug extended from one stop flange and fastened to a lug at the holder frame. Further, the holder frame, the locating plate and the locking block are respectively made of iron for the advantages of low cost and high structural strength.